Rotor cooling system for a centrifugal rotary fiberizing unit

ABSTRACT

The rotor of a fiberization unit for the centrifugal formation of termoplastic filaments has an improved cooling system to cool the base and the peripheral wall of the rotor. A coolant chamber beneath the base cools the base and arcuate cooling chambers at the upper extremity of the peripheral wall cool the wall and radially directed orifices in the wall from which filaments are ejected.

United States Patent Pallo Nov. 27, 1973 [5 ROTOR COOLING SYSTEM FOR A 2,944,284 7/1960 Tillotson et a1 65/14 x CENTRIFUGAL ROTARY FIBERIZING 3,282,667 1 1/1966 Stalego et a1. 65/12 X 3,542,533 11/1970 Hesse 65/16 x UNIT Inventor: John M. Pallo, Washington, NJ.

Johns-Manville Corporation, New York, N.Y.

Filed: Feb. 22, 1972 Appl. No.: 227,901

Assignee:

References Cited UNITED STATES PATENTS 1/1953 Heymes et al. 65/6 Primary Examiner-Robert L. Lindsay, Jr. Attorney-John A. Mc Kinney et a1.

[5 7] ABSTRACT The rotor of a fiberization unit for the centrifugal formation of termoplastic filaments has an improved cooling system to cool the base and the peripheral wall of the rotor. A coolant chamber beneath the base cools the base and arcuate cooling chambers at the upper extremity of the peripheral wall cool the wall and radially directed orifices in the wall from which filaments are ejected.

7 Claims, 5 Drawing Figures ROTOR COOLING SYSTEM FOR A CENTRIFUGAL ROTARY FIBERIZING UNIT BACKGROUND OF THE INVENTION The present invention relates to rotor cooling systems for centrifugal rotary fiberizing units and in particular to a system for cooling both the base and peripheral walls of the rotor.

Two conventional methods for producing refractory fibers are the spinning and steam blown methods. However, these methods generally yield a product having a shot content varying from 60 percent to 80 percent, with the remainder being fiber. Thus, the shot and fiber must be processed to yield a product having between 25 percent shot. In this shot removal process a large percentage of fiber is degraded and lost. Thus there has been a need to provide a method and apparatus which produce a product essentially free of shot to thereby eliminate the need for further processing before the product can be filtered.

Centrifugal rotor fiberizing systems for the manufacture of thermoplastic glass fibers and the like are also used in the industry. In these units molten material (e.g. glass) is deposited on the bottom of a rotor and flows by centrifugal force outward to orifices in a peripheral wall of the rotor. Then, the material is ejected through the orifices by the centrifugal force to form primary fibers. These primary fibers are attenuated into fine fibers by means of an impinging gaseous blast.

The characteristics of the primary filaments issuing from the rotor orifices at any given viscosity, temperature and centrifugal force is directly related to the diameters of the orifices. Thus, excessive amounts of shot are produced when the diameters of the orifices increase due to erosion of the orifice walls. Although the diameters of the orifices can be initially made to precise dimensions, continuous exposure to the very agres' sive conditions of high temperature abrasive melts have previously rapidly and erratically eroded away the walls of the orifices when base metals were used. The erosion not only enlarged the orifices but distorted their shape thereby causing a degrading of the fibrous product and the formation of shot.

Attempts have been made to solve this problem through the use of erosion resistant orifice inserts. However, these inserts are made of extremely costly metals such as platinum and consequently they are not a very satisfactory solution.

Another approach to this problem has been the use of annular cooling chambers in the peripheral walls of the rotors with the orifices extending through the cooling chambers. One such arrangement is shown in the U.S. Pat. of WK. Hesse, No. 3,542,533; issued Nov. 24, 1970. The present invention also uses cooling chambers to keep the rotor at the proper temperature, but the arrangement used in the present invention is quite distinct from any known system including the above mentioned patent.

SUMMARY OF THE INVENTION This invention comprises an improved cooling system for the rotor of a centrifugal high temperature rotary fiberizing unit. The rotor has a base on which the glass melt is deposited and a peripheral wall with orifices therein through which the melt passes to form the primary fibers. A cooling chamber is located beneath the base of the rotor to maintain the base at a desired temperature as the molten material flows over the base to the peripheral wall. A plurality of arcuate cooling chambers are located about an upper extremity of the peripheral wall to maintain the surfaces of the orifices in the peripheral wall at the desired temperature. These arcuate chambers are divided into inner and outer conduits with inlet ports and outlet ports connected respectively to the inner and outer conduits and located intermediate the ends of the arcuate chambers. The coolant flows into the chamber beneath the base and from this chamber to the inlets of the various arcuate chambers. There the fiow of coolant is divided and flows through the inner conduits and back through the outer conduits to the outlets which are vented.

One object of this invention is to provide a rotor for a centrifugal rotor fiberizing system which is made of a base metal and will continuously produce a relatively shot-free refractory fiber product.

BRIEF DESCRIPTION OF THE DRAWINGS The above mentioned objects and advantages will be more apparent and additional objects and advantages will become apparent from the following detailed description and the accompanying drawings wherein:

FIG. 1 is a plan view of the preferred rotor of the present invention;

FIG. 2 is an elevational view, partly in section, taken substantially along lines 2-2 of FIG. 1;

FIG. 3 is a fragmentary view taken substantially along lines 3-3 of FIG. 1;

FIG. 4 is a fragmentary view taken substantially along lines 4-4 of FIG. 1; and

FIG. 5 is a fragmentary view taken substantially along lines 5-5 of FIG. 1.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIGS. 1 and 2 of the drawings, a centrifugal rotor 20 is mounted on a drive shaft 22. The drive shaft is mounted in conventional bearings (not shown) and is rotated at a predetermined high speed by a motor or similar drive means. The drive shaft 22 has an upper portion 24 and a lower portion 26 of a smaller diameter. The rotor 20 is carried on the lower portion 26 with the upper surface of the rotor hub 28 abutting an annular shoulder 30 between portions 24 and 26 of the drive shaft. The lower section of portion 26 is threaded and the rotor is held tightly in place by a nut 32 so that the rotor 20 will not rotate relative to the shaft 22. To insure that the rotor 20 will not rotate relative to the shaft 22 and to properly align the rotor with the shaft a complimentary axially extending key and keyway or similar means can be provided on the interior surface of rotor hub 28 and the exterior surface of the lower portion 26 of the drive shaft.

The drive shaft 22 has an axially extending central bore 36 for carrying coolant to the rotor. The bore 36 extends down through the upper portion 24 of the shaft and terminates in the lower portion 26 of the shaft. Adjacent the lower end of the bore 36 and below the annular shoulder 30 of the shaft a plurality of radially extending ports 38 extend between the bore 36 and the outer surface of the shaft. These radial ports 38 supply coolant to radially extending supply ports in the rotor hub 28. While the drawings illustrate four ports 38 in the shaft and four corresponding ports 40 in the hub, it is to be understood that any number of ports can be used to supply coolant to the rotor as long as they are capable of delivering the required amount of coolant.

The rotor has an annular base 42 which extends intermediate the upper portion of hub 28 and an annular peripheral wall 44; a series of arcuate cooling chambers 46 adjacent the upper portion of the peripheral wall 44; a conical cover 48 extending inwardly and upwardly from the arcuate cooling chambers; and an inverted conical wall 50 extending downwardly and inwardly from the lower portion of the peripheral wall 44 to a lower portion of hub 28. Wall 50 of the unit is strengthened by means of reinforcing strips 78 spaced 90 apart and 45 degrees from the supply ports 40.

An exterior surface of hub 28, a lower surface of base 42, an upper surface of wall 50, and an inner surface of wall 44 intermediate base 42 and wall 50 define an annular cooling chamber 52. Cooling chamber 52 cools the base 42 and connects the inlet ports 54 of the arcuate cooling chambers 46 with the supply ports 40 of the hub 28.

The arcuate cooling chambers 46 in the embodiment shown in the drawings each extend one quarter of the way around the periphery of the rotor. The chambers are separated by radially extending vertical plates 56. Each chamber 46 has an arcuate wall 58 which extends substantially the entire length of the chamber and divides the chamber into inner and outer conduits 60 and 62 respectfully. The ends of arcuate walls 58 are spaced from plates 56 thereby forming ports 64 at each end of chamber 46 innerconnecting the inner and outer conduits 60 and 62.

The inlet ports 54 and outlet ports 66 of the cooling chambers 46 are located midway between the ends of the cooling chambers. The inlet and outlet ports 54 and 66 pass vertically through enlarged portions of the rotor wall 44. The lower end of each inlet port 54 communicates with the annular cooling chamber 52 while the upper end of each inlet port communicates with one of the inner conduits 60. The upper end of each outlet port 66 communicates with one of the outer conduits 62, while the lower end of each of the outlet port 66 communicates with one of a plurality of exhaust lines 68 which are located in wall 50. Exhaust lines 68 extend radially inward from the exhaust ports 66 to exhaust ports 70 in the drive shaft 22. The exhaust ports 70 in turn communicate with vertically extending exhaust lines 72 which are vented to the atmosphere at the lower end of the drive shaft.

In operation the rotor is loaded by a molten stream of material which is deposited off center into an interior cavity of the rotor defined by the peripheral wall of drive shaft 22, the base plate 42, the inner surface of peripheral rotor wall 44 and the cover 48. The molten material upon entering the rotor cavity can either fall directly onto the base plate 42 or onto a low heat conducting refractory sheet not shown that covers the base plate 42. The molten material then flows laterally by centrifugal force to the orifices 74 in the peripheral wall 44 of the rotor.

The molten material then flows through the orifices 74 and is formed into primary fibers. These primary fibers are further attenuated by means of hot gases or steam from an attenuating burner 76.

To maintain the rotor at the proper temperature a suitable coolant such as water, steam, and the like, is pumped (by a pump not shown) through the bore 36 and ports 38 in the drive shaft 22 and out through ports 40 of rotor hub 28 into the annular chamber 52. The

coolant within chamber 52 maintains the base plate 42 within the desired temperature range. From the chamber 52 the coolant flows outward to the four inlet ports 54, of the different arcuate cooling chambers 46. The coolant flows upward through the inlet ports 54 and into the inner conduits of the arcuate cooling chambers. In the inner conduits 60 the coolant flows in opposite circumferential directions away from the inlet ports 54 until the coolant reaches separating plates 56. Then the coolant passes radially outward through ports 64 and then in a circumferential direction back toward outlet ports 66. The coolant in the arcuate cooling chambers cools the upper portion of the rotor and the orifices in the adjacent peripheral wall 44. The coolant exits through outlet ports 66, passes radially inward through bores 68 and out through bores 72 of the drive shaft to the atmosphere.

From the above description, it is clear that the rotor can be made of a precast or welded construction using a base metal or combinations of metal capable of being preheated to about 2,000 fahrenheit by any conventional method such as hot gases, induction heating, flame heating, and the like. The peripheral wall 44 can contain a single row or a plurality of rows of orifices 74 and is divided into arcuate sections, each of which is provided with its own arcuate cooling chamber. While in the preferred embodiment there are four arcuate cooling chambers, it is to be understood that the number of arcuate chambers can very.

The cooling chamber arrangement of the present invention enables the use of base metals instead of noble metals and the rotor can be used in an inert atmosphere to produce fibers from high temperature refractory melts. The fibers produced are essentially free of shot, thereby eliminating the need for further processing and enabling the product to be directly felted.

What I claim is:

1. In an apparatus for use in rotary systems of fiberization wherein a supply of molten material is deposited on a circular base of a rotating rotor and urged by the centrifugal force of rotation through orifices in a peripheral wall of the rotor extending upward from the base to produce filaments of molten material for attenuation into fibers, the improvement comprising: a base cooling chamber having the base as its upper surface; the peripheral wall of the rotor having orifices located in an intermediate portion of said peripheral wall which is free of cooling chamber means and between upper and lower extremities of said peripheral wall, said peripheral wall having annular cooling chamber means at said upper extremity for removing heat through conduction from the intermediate portion of said peripheral wall, said annular cooling chamber means having inlet means connected to said base cooling chamber; said annular cooling chamber means having outlet means; and means for effecting the circulation of coolant through said base cooling chamber and said annular cooling chamber means.

2. In the apparatus of claim 1: said annular cooling chamber means comprising a plurality of arcuate cooling chambers.

3. In the apparatus of claim 2: said arcuate cooling chambers each having an arcuate wall dividing each of said arcuate cooling chambers into inner and outer conduits, said inner and outer conduit of each arcuate cooling chamber being connected by ports to permit the circulation of coolant therethrough from said inlet means which is connected to one of said conduits to said outlet means which is connected to the other of conduits.

4. In the apparatus of claim 3: said inlet means comprising a plurality of inlet ports with one of said inlet ports being connected to each of said inner conduits of said arcuate cooling chambers intermediate ends of said inner conduits, said outlet means comprising a plurality of outlet ports with one of said outlet ports being connected to each of said outer conduits of said arcuate cooling chambers intermediate ends of said outer conduits, and said ports connecting said inner and outer conduits being located at the ends of each of said cooling chambers.

5. In the apparatus of claim 4: said outlet means being vented to the atmosphere.

6. In the apparatus of claim 1: said base cooling chamber being an annular chamber, defined by an outer surface a hub of the rotor, an underside of the base, an upper surface of a bottom wall and a portion of the peripheral wall intermediate said base and said bottom wall.

7. In the apparatus of claim 6: said rotor being mounted on a shaft having a coolant supply bore therein, and said base cooling chamber being connected to said coolant supply bore in said shaft by supply ports in said hub. 

1. In an apparatus for use in rotary systems of fiberization wherein a supply of molten material is deposited on a circular base of a rotating rotor and urged by the centrifugal force of rotation through orifices in a peripheral wall of the rotor extending upward from the base to produce filaments of molten material for attenuation into fibers, the improvement comprising: a base cooling chamber having the base as its upper surface; the peripheral wall of the rotor having orifices located in an intermediate portion of said peripheral wall which is free of cooling chamber means and between upper and lower extremities of said peripheral wall, said peripheral wall having annular cooling chamber means at said upper extremity for removing heat through conduction from the intermediate portion of said peripheral wall, said annular cooling chamber means having inlet means connected to said base cooling chamber; said annular cooling chamber means having outlet means; and means for effecting the circulation of coolant through said base cooling chamber and said annular cooling chamber means.
 2. In the apparatus of claim 1: said annular cooling chamber means comprising a plurality of arcuate cooling chambers.
 3. In the apparatus of claim 2: said arcuate cooling chambers each having an arcuate wall dividing each of said arcuate cooling chambers into inner and outer conduits, said inner and outer conduit of each arcuate cooling chamber being connected by ports to permit the circulation of coolant therethrough from said inlet means which is connected to one of said conduits to said outlet means which is connected to the other of conduits.
 4. In the apparatus of claim 3: said inlet means comprising a plurality of inlet ports with one of said inlet ports being connected to each of said inner conduits of said arcuate cooling chambers intermediate ends of said inner conduits, said outlet means comprising a plurality of outlet ports with one of said outlet ports being connected to each of said outer conduits of said arcuate cooling chambers intermediate ends of said outer conduits, and said ports connecting said inner and outer conduits being located at the ends of each of said cooling chambers.
 5. In the apparatus of claim 4: said outlet means being vented to the atmosphere.
 6. In the apparatus of claim 1: said base cooling chamber being an annular chamber, defined by an outer surface a hub of the rotor, an underside of the base, an upper surface of a bottom wall and a portion of the peripheral wall intermediate said base and said bottom wall.
 7. In the apparatus of claim 6: said rotor being mounted on a shaft having a coolant supply bore therein, and said base cooling chamber being connected to said coolant supply bore in said shaft by supply ports in said hub. 